support perf trampoline on -linux-musl

Feature or enhancement

Proposal:

currently the autotools does the following check

AS_CASE([$PLATFORM_TRIPLET],
  [x86_64-linux-gnu], [perf_trampoline=yes],
  [aarch64-linux-gnu], [perf_trampoline=yes],
  [perf_trampoline=no]
)

simply making it

AS_CASE([$PLATFORM_TRIPLET],
  [x86_64-linux-gnu], [perf_trampoline=yes],
  [x86_64-linux-musl], [perf_trampoline=yes],
  [aarch64-linux-gnu], [perf_trampoline=yes],
  [aarch64-linux-musl], [perf_trampoline=yes],
  [perf_trampoline=no]
)

makes the trampoline build on musl libc systems too, and it seems to work fine: https://img.ayaya.dev/yT9j39Lfeb8u

it doesn't seem like the assembly actually depends on libc support. maybe it should check -linux-* instead?

in any case just adding the above triples seems to work ok, unless i'm missing something, so it would be nice if it was added :)

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-122370
• gh-153424
• gh-153457

Locate the autotools check using AS_CASE([$PLATFORM_TRIPLET]) described in the issue, then review linked PRs gh-122370, gh-153424, and gh-153457 first. Confirm the supported musl triples and validate the trampoline build on the affected Linux-musl platforms; done means the build succeeds with perf_trampoline enabled.